This invention is in the fields of automobile safety, intelligent highway safety systems, accident avoidance, accident elimination, collision avoidance, blind spot detection, anticipatory sensing, automatic vehicle control, intelligent cruise control, automotive navigation and other automobile and truck safety, navigation and control related fields.
There are two major efforts underway that will significantly affect the design of automobiles and highways. The first is involved with preventing deaths and serious injuries from automobile accidents. The second involves the attempt to reduce the congestion on highways. In the first case, there are approximately forty thousand (40,000) people killed each year in the United States by automobile accidents and another several hundred thousand are seriously injured. In the second case, hundreds of millions of man-hours are wasted every year by people stuck in traffic jams on the world""s roadways. There have been many attempts to solve both of these problems; however, no single solution has been able to do so.
When a person begins a trip using an automobile, he or she first enters the vehicle and begins driving, first out of the parking space and then typically onto a local or city road and then onto a highway. In leaving the parking space, he or she may be at risk from an impact of a vehicle traveling on the road. The driver must check his or her mirrors to avoid such an event and several electronic sensing systems have been proposed which would warn the driver that a collision is possible. Once on the local road, the driver is at risk of being impacted from the front, side and rear, and electronic sensors are under development to warn the driver of such possibilities. Similarly, the driver may run into a pedestrian, bicyclist, deer or other movable object and various sensors are under development which will warn the driver of these potential events. These various sensors include radar, optical, ultrasonic, and a variety of others sensors, each of which attempts to solve a particular potential collision event. It is important to note that in none of these cases is there sufficient confidence in the decision that the control of the vehicle is taken away from the driver.
In some proposed future Intelligent Transportation System (ITS) designs, hardware of various types is embedded into the highway and sensors which sense this hardware are placed onto the vehicle so that it can be accurately guided along a lane of the highway. In various other systems, cameras are used to track lane markings or other visual images to keep the vehicle in its lane. However, for successful ITS, additional information is needed by the driver, or the vehicle control system, to take into account weather, road conditions, congestion etc., which typically involves additional electronic hardware located on or associated with the highway as well as the vehicle. From this discussion, it is obvious that a significant number of new electronic systems are planned for installation onto automobiles. However, to date, no product has been proposed or designed which combines all of the requirements into a single electronic system. This is the intent of this invention.
The safe operation of a vehicle can be viewed as a process in the engineering sense. To achieve safe operation, first the process must be designed and then a vehicle control system must be designed to implement the process. The goal of a process designer is to design the process so that it does not fail. The fact that so many people are being seriously injured and killed in traffic accidents and the fact that so much time is being wasted in traffic congestion is proof that the current process is not working and requires a major redesign. To design this new process the information required by the process must be identified, the source of that information determined and the process designed so that the sources of information can communicate effectively to the user of the information, which will most often be the vehicle control system. Finally, the process must have feedback that self-corrects the process when it is tending toward failure.
Although it is technologically feasible, it is probably socially unacceptable at this time for a vehicle safety system to totally control the vehicle. The underlying premise of this invention, therefore, is that people will continue to operate their vehicle and control of the vehicle will only be seized by the control system when such an action is required to avoid an accident or when such control is needed for the orderly movement of vehicles through potentially congested areas on a roadway. When this happens, the vehicle operator will be notified and given the choice of exiting the road at the next opportunity. In some implementations, especially when this invention is first implemented on a trail basis, control will not be taken away from the vehicle operator but a warning system will alert the driver of a potential collision.
Consider several scenarios and what information is required for the vehicle control process to prevent accidents. In one case, a driver is proceeding down a country road and falls asleep and the vehicle begins to leave the road, perhaps heading toward a tree. In this case, the control system would need to know that the vehicle was about to leave the road and for that it must know the position of the vehicle relative to the road. One method of accomplishing this would be to place a wire down the center of the road and to place sensors within the vehicle to sense the position of the wire relative to the vehicle. An alternate approach would be for the vehicle to know exactly where it is on the surface of the earth and to also know exactly where the edge of the road is. These approaches are somewhat different because in the former solution every road in the world would require the placement of appropriate hardware as well as the maintenance of this hardware. This is obviously impractical. In the second case, the use of the global positioning satellite system (GPS), augmented by additional systems to be described below, will provide the vehicle control system with an accurate knowledge of its location. Whereas it would be difficult to install and maintain hardware such as a wire down the center of the road for every road in the world, it is not difficult to survey every road and record the location of the edges, and the lanes for that matter, of each road. This information must then be made available through one or more of a variety of techniques to the vehicle control system.
Another case might be where a driver is proceeding down a road and decides to change lines while another vehicle is in the driver""s blind spot. Various companies are developing radar, ultrasonic or optical sensors to warn the driver if the blind spot is occupied. The driver may or may not heed this warning, perhaps due to an excessive false alarm rate, or he or she may have become incapacitated, or the system may fail to detect a vehicle in the blind spot and thus the system will fail. Consider an alternative technology where again each vehicle knows precisely where it is located on the earth surface and additionally can communicate this information to all other vehicles within a certain potential danger zone relative to the vehicle. Now, when the driver begins to change lanes, his or her vehicle control system knows that there is another vehicle in the blind spot and therefore will either warn the driver or else prevent him or her from changing lanes thereby avoiding the accident. Similarly, if a vehicle is approaching a stop sign or red traffic light and the operator fails to bring the vehicle to a stop, if the existence of this traffic light or stop sign has been made available to the vehicle control system, the system can warn the driver or seize control of the vehicle to stop the vehicle and prevent a potential accident. Additionally, if an operator of the vehicle decides to proceed across an intersection without seeing an oncoming vehicle, the control system will once again know the existence and location and perhaps velocity of the oncoming vehicle and warn or prevent the operator from proceeding across the intersection.
Consider another example where water on the surface of a road is beginning to freeze. Probably the best way that a vehicle control system can know that the road is about to become slippery, and therefore that the maximum vehicle speed must be significantly reduced, is to get information from sensors located on the highway that are capable of determining this condition and communicating it to the vehicle. Alternately, a local weather station can determine that such conditions are likely to exist and communicate that information to every vehicle in the area. A set of sensors could be placed on each vehicle but since all vehicles in the area would need the identical information and since the maximum vehicle speed is to be controlled, it is both costly and inaccurate to rely on vehicle resident sensors. Nevertheless, an alternate approach is to put temperature and humidity sensors on each vehicle and provide for that information to be communicated between vehicles when necessary.
Countless other examples exist, however, from those provided above it can be seen that for the vehicle control system to function without error, certain types of information must be accurately provided. These include information permitting the vehicle to determine its absolute location and means for vehicles near each other to communicate this location information to each other. Additionally, map information that accurately provides boundary and lane information of the road must be available. Also, critical weather or road-condition information is necessary. The road location information need only be generated once and changed whenever the road geometry is altered. This information can be provided to the vehicle through a variety of techniques including prerecorded media such as CD-ROMs or through communications from transmitters located in proximity to the vehicle, satellites, radio and cellular phones.
Many roads in the world are congested and are located in areas where the cost of new road construction is prohibitive or such construction is environmentally unacceptable. It has been reported that an accident on such a highway typically ties up traffic for a period of approximately four times the time period required to clear the accident. Thus, by eliminating accidents, a substantial improvement in the congested highway problem results. This of course is insufficient. On such highways each vehicle travels with a different spacing, frequently at different speeds and in the wrong lanes. If the proper spacing of the vehicles could be maintained, and if the risk of an accident could be substantially eliminated, vehicles under automatic control could travel at substantially higher velocities and in a more densely packed configuration thereby substantially improving the flow rate of vehicles on the highway by as much as a factor of 3 to 4 times. This not only will reduce congestion but also improve air pollution. Once again, if each vehicle knows exactly where it is located, can communicate its location to surrounding vehicles and knows precisely where the road is located, then the control system in each vehicle has sufficient information to accomplish this goal.
The information listed above may still be insufficient. The geometry of a road or highway can be determined once and for all until erosion or construction alters the road. Properly equipped vehicles can know their location and transmit that information to other properly equipped vehicles. There remains a variety of objects whose location is not fixed, which have no transmitters and which can cause accidents. These objects include broken down vehicles, animals such as deer which wander onto highways, pedestrians, bicycles, objects which fall off of trucks, and especially other vehicles which are not equipped with location determining systems and transmitters for transmitting that information to other vehicles. Part of this problem can be solved for congested highways by restricting access to these highways to vehicles that are properly equipped. Also, these highways are typically in urban areas and access by animals can be effectively eliminated. Heavy fines can be imposed on vehicles that drop objects onto the highway. Finally, since every vehicle operator becomes part of the process, each such operator becomes a potential source of information to help prevent catastrophic results. Thus, each vehicle should also be equipped with a system of essentially stopping the process in an emergency. Such a system could be triggered by the operator strongly applying the brakes, rapidly turning the steering wheel or by activating a manual switch when the operator observes a critical situation but is not himself in immediate danger. An example of the latter case is where a driver witnesses a box falling off of a truck in an adjacent lane.
To solve the remaining problems, therefore, each vehicle should also be equipped with an anticipatory collision sensing system, or collision forecasting system, which is capable of identifying or predicting and reacting to a pending accident. As the number of vehicles equipped with the control system increases, the need for the collision forecasting system will diminish.
Once again, the operator will continue to control his vehicle provided he or she remains within certain constraints. These constraints are like a corridor. As long as the operator maintains his vehicle within this allowed corridor, he or she can operate that vehicle without interference from the control system. That corridor may include the entire width of the highway when no other vehicles are present or it may be restricted to all East-bound lanes, for example. In still other cases, that corridor may be restricted to a single line and additionally, the operator may be required to keep his vehicle within a certain spacing tolerance from the preceding vehicle. If a vehicle operator wishes to exit a congested highway, he could operate his turn signal that would inform the control system of this desire and permit the vehicle to safely exit from the highway. It can also inform other adjacent vehicles of the operator""s intent, which could then automatically cause those vehicles to provide space for lane changing, for example. The highway control system is thus a network of individual vehicle control systems rather than a single highway resident computer system.
The complete disclosure of the following patents is incorporated by reference herein in its entirety. Also, the systems disclosed in the patents may be used in the invention in appropriate part.
U.S. Pat. Nos. 4,352,105 and 4,298,280 to Harney describe an infrared radar system and a display system for use by aircraft. In particular, these patents discloses an infrared radar system that provides high resolution, bad whether penetration, day-night operation and which can provide simultaneous range, intensity and high resolution angular information. The technology uses CO2 laser and a 10.6 micron heterodyne detection. It is a compact imaging infrared radar system that can be used with the invention described herein. Harney applies this technology to aircraft and does not contemplate its application to collision avoidance or for information transmission for automobiles.
U.S. Pat. No. 4,521,861 to Logan, describes a method and apparatus for enhancing radiometric imaging. This invention discloses a method and apparatus for enhancing target detection through the utilization of an imaging radiometer. The radiometer, which is a passive thermal receiver, detects the reflected and emitted thermal radiation of targets. Prior to illumination, foliage will appear hot due to its high emissivity and metals will appear cold due to their low emissivities. When the target is momentarily illuminated foliage appears dark while metals appear hot. By subtracting the unilluminated image from the illuminated image, metal targets are enhanced. The teachings of this patent thus have applicability to the instant invention as discussed below.
U.S. Pat. No. 5,272,483 to Kato describes an automobile navigation system. This invention attempts to correct for the inaccuracies in the GPS system through the use of an inertial guidance, geomagnetic sensor, or vehicle crank shaft speed sensor. However, it is unclear as to whether the second position system is actually more accurate than the GPS system. This combined system, however, cannot be used for sub-meter positioning of an automobile.
U.S. Pat. Nos. 5,314,037 and 5,529,138 to Shaw et al. describe a collision avoidance system using laser radar and a laser gyroscope. The following paragraphs are quoted from U.S. Pat. No. 5,314,037 that provides an excellent background the collision avoidance prior art.
xe2x80x9cThe use of radars in collision avoidance systems is generally known. U.S. Pat. No. 4,403,220 dated Sep. 6, 1983 discloses a radar system adapted to detect relative headings between aircraft or ships at sea and a detected object moving relative to the ground. The system is adapted to collision avoidance application. U.S. Pat. No. 4,072,945 dated Feb. 7, 1978 discloses a radar operated collision avoidance system for roadway vehicles. The system senses the vehicle speed relative to an object and its distance and decides whether the vehicle is approaching the object at a dangerously high speed. A minimum allowable distance represented by a digital code is stored in a memory of a computer and the minimum allowable distance is compared with the distance sensed by the radar.xe2x80x9d
xe2x80x9cMost of the prior art collision avoidance systems use microwave radars as the ranging and detecting device. There are multiple disadvantages of these automobile collision avoidance systems when microwave radars are used. One major disadvantage is related to the beam width, that is the angular width of the main lobe of the radar, and the associated angular resolution of the microwave radar. The beam width is inversely proportional to the antenna diameter in wavelength. With the limitation of the antenna size, it is very difficult to make a reasonable size microwave radar with beam width less than 3 degrees. At the desired scanning distance, this beam width will scan an area that is much too big and thus is too nonspecific and difficult to differentiate the received echoes. Besides getting echo from another car in front of it, this radar will also receive echoes from roadside signs, trees or posts, or bridges overpassing an expressway. On highways with divided lanes the microwave radar will receive echoes from cars 2 or 3 lanes away and has difficulty to in differentiating them from echoes coming from objects in the same lane. Because of the poor angular resolution of microwave radars, the direction of objects can not be specifically determined and objects too close to one another cannot be separated. The angular resolution of microwave radars is not small enough for them to be effectively used to monitor roadway traffic. The other disadvantage is that the microwave radars have difficulty in distinguishing radar signals coming from adjacent cars with similar equipment. If there are more than two cars with the same radar equipment on the same scene, the signals become very confusing.xe2x80x9d
In the Shaw invention laser radars are used as scanning and ranging devices. These laser radar devices have much smaller beam and angular resolution and give more specific and precise information of the detected object""s direction and distance. Laser radars will also be used in the invention disclosed herein but in a somewhat different manner. Here, the laser radars will obtain many measurements from many points on an object and use the information to form a three dimensional representation of the object. Also, the vectorial velocity in general will be obtained by a comparison of points on this image over time. In this manner only a single laser radar unit is required rather than at least two in the case of Shaw.
Shaw also discloses the use of a steering wheel rotation sensor, however, the laser gyro is preferred since the directional information is much more reliable.
xe2x80x9cRadars have been used widely in detection of speed and distance of moving objects. Most radars use electromagnetic waves in the microwave frequency range. They are divided into pulse radars and continuous radars. In a pulse radar, the transmitter sends out radar signals through the antenna in pulses with extremely short duration, millionth of a second for example. The next pulse is emitted after the echoes have been received. The radars use Doppler principle to calculate the speed by the amount of frequency shift. The Doppler shift is caused by the targets moving toward or away from the radar in the radar""s radial direction. Pulse radar can detect the speed and distance of a target. A simple continuous wave radar can give the speed information, but not the distance information. A frequency modulated continuous wave radar can detect both the speed and the distance.xe2x80x9d
xe2x80x9cThe angular resolution of a radar depends on the beam width. If two targets are at about the same distance but at slightly different angles, they can be separated if they are more than one beam width apart. Ambiguity sometimes occurs due to reception of echoes from targets beyond the range of interest and of second time-around echoes. This can be resolved by range gates that make radar insensitive to targets beyond the range of interest. The range ambiguity can also be resolved by filters that put limits on range.xe2x80x9d
The xe2x80x9claser was invented in 1960. Laser light differs from ordinary light in a few areas. The most important difference is that laser light is highly directional. The laser light travels as parallel beam and spreads very little. It can travel in very narrow beams. Laser light is also, electromagnetic waves. In comparison to microwave, laser light has higher frequency and shorter wavelength. Laser light can be used to measure speed and distance in the same way as the microwave radar. For example, YAG (crystalline yttrium aluminum garnet) laser and ruby laser have been used as range finders. The YAG can emit very efficient and useful laser in the near infrared at 1.06 micrometer wavelength.xe2x80x9d
xe2x80x9cSemiconductor junction lasers or diode lasers are very small, one millimeter or even smaller, typically, emitting about 10 milliwatts of power and can be produced inexpensively. A light-weight laser radar sensory device has been developed for use in special canes for the blind, with two or three Gallium Arsenide lasers. It is low-powered and its safety has been proven for outdoor and indoor daily living usage. Gallium arsenide laser is one example of the semiconductor lasers. The semiconductor lasers are usually very small, less than one millimeter in any direction. They can be easily assembled into compact arrays of many units. With heterostructure, gallium arsenide (GaAs) lasers can operate continuously in room temperature. The laser light can be modulated by varying the diode current. By alloying different proportions of two semiconductors, diode lasers can be fabricated to radiate at any wavelength from 0.64 to 32 micrometers. For example, the heterostructure of gallium indium arsenide phosphide sandwiched between layers of indium phosphide can radiate at 1.3 micrometers.xe2x80x9d
xe2x80x9cThe laser beams are highly directional. The laser receiving equipment are also highly directional. Since the laser receiving equipment will receive only the laser beams aimed at it, most interference can be avoided. This is an important advantage over the microwave radar. When there are multiple cars with the same laser radars at the same scene, their reflected signals will not interfere with each other. Confusion can be easily avoided.xe2x80x9d
The xe2x80x9claser gyroscope is the modern type of gyroscope with higher degree of accuracy, cheaper and much smaller than the traditional mechanical gyroscope. It can give directional information precisely. A typical laser gyroscope is made of glass-like material and is shaped like a triangle or a rectangle. A laser beam is generated and split into two parts that travel in opposite directions around the triangle or rectangle. Laser gyroscope has been used by airlines as automatic pilots to keep the airplanes on course. If the aircraft moves off course, the movement to one side will make one laser beam travel further than the other. Computer can analyze how much the laser beams are out of step and compute the plane""s change in direction. Therefore, laser gyroscope can sense the rotation rate or direction change rate accurately.xe2x80x9d
xe2x80x9cIt is well known that laser beams are highly directional. For example, a beam of 1 inch in diameter may, at most, spread to only 3 inches after traveling one mile. Because the laser beam is highly directional and the beam width is very narrow, the scanning zone . . . can be easily controlled and be highly specific and selective.xe2x80x9d
In the Shaw invention, xe2x80x9c . . . laser radars which emit electromagnetic waves in the infrared range or the far infrared range will be utilized. Laser lights do not penetrate rain, sandstorm, fog or snow, etc. as well as microwave radar. However, infrared light will penetrate rain, sandstorm, fog or snow better than the visible light. Therefore, the rain or snow, etc. will affect the driver""s vision much more than they affect the infrared laser radar. If the rain or snow etc. are heavy enough, they may reduce the effective range of the laser radar. In this situation, the driver""s vision will be affected even more such that the driver should slow down the car speed. With reduced car speed, the reduced range of laser radar can still serve its function.xe2x80x9d
xe2x80x9cWith highly directional character and with very small beam width, laser radars have other advantages as compared with microwave radars. The laser radar can easily avoid confusion caused by reflections from other laser radars in the vicinity. For microwave radars, reflected signals from adjacent vehicle with same or similar radar equipment can be received and become very confusing. Laser radars can avoid this disadvantage. The receiver of the laser radar is aimed at exactly the same direction as the associated transmitter. The receiver is also highly directional. The receiver will not receive the reflected back laser light emitted from other transmitters on the same vehicle or from transmitters on adjacent vehicles because ordinarily the other laser light reflection will come in a direction different from the receivers direction, with the following two very rare and brief exceptions. The first exception is that confusion may occur when an oncoming vehicle""s laser beam happen to aim at the system-equipped vehicle""s receiver. In two moving cars this situation will last at most only a minimal fraction of a second. A second exception is that confusion may occur when an adjacent vehicle""s laser beam happens to illuminate at the same spot as the spot illuminated by the system-equipped vehicle""s laser beam. Then the reflected laser light from the adjacent vehicle may come in the right direction for the system-equipped vehicle""s receiver. Again, this situation should be very rare and should last for an extremely short period of time. Since these two situations are extremely rare and very brief, confusion and interference from adjacent vehicle""s similar laser radar equipment virtually will not be a problem for laser radars in this invention.xe2x80x9d
Shaw, in these patents, relies on two laser radar systems in order to get an accurate prediction of the location of the vehicle on the roadway using triangulation. No image of vehicles or other objects on the roadway is formed. No attempt is made to identify the illuminated object. Shaw uses triangulation from two laser radars to obtain the relative velocity of the object being interrogated whereas in the instant invention, the motion over time of the object can be used to obtain its vector velocity.
U.S. Pat. No. 5,367,463 to Tsuji describes a vehicle azimuth determining system. It uses regression lines to find vehicle on map when there are errors in the GPS and map data. This patent does not give sub-meter accuracy. The advantage of this invention is that it shows a method of combining both map matching data and GPS along with a gyro and a vehicle velocity and odometer data to improve the overall location accuracy of the vehicle.
U.S. Pat. No. 5,383,127 to Shibata uses map matching algorithms to correct for errors in the GPS navigational system to provide a more accurate indication of where the vehicle is or, in particular, on what road the vehicle is. This procedure does not give sub-meter accuracy. Its main purpose is for navigation and, in particular, in determining the road on which the vehicle is traveling.
U.S. Pat. No. 5,416,712 to Geier, et al. relates generally to navigation systems and more specifically to global positioning systems that use dead reckoning apparatus to fill in as backup during periods of GPS shadowing such as occur amongst obstacles, e.g., tall buildings in large cities. This patent shows a method of optimally combining the information available from GPS even when less than 3 or 4 satellites are available with information from a low-cost, inertial gyro, having errors that range from 1-5%. This patent provides and excellent analysis of how to use a modified Kalman filter to optimally use the available information.
U.S. Pat. No. 5,463,384 to Juds uses a plurality of infrared beams to alert a truck driver that a vehicle is in his blind spot when he begins to turn the vehicle. The system is typically activated by the vehicle""s turn signal. No attempt is made to measure exactly where the object is, only whether it is in the blind spot or not.
U.S. Pat. No. 5,467,072 to Michael relates to a phased array radar system that permits the steering of a radar beam without having to rotate antennas. Aside from that, it suffers from all the disadvantages of radar systems as described above. In particular, it is not capable of giving accurate three-dimensional measurements of an object on the roadway.
U.S. Pat. No. 5,479,173 to Yoshioka, et al. uses a steering angle sensor, a yaw rate sensor and a velocity of the vehicle sensor to predict the path that the vehicle will take. It uses a radar unit to identify various obstacles that may be in the path of the vehicle, and it uses a CCD camera to try to determine that the road is changing direction in front of the vehicle. No mention is made of the accuracy with which these determinations are made. It is unlikely that sub-meter accuracy is achieved.
U.S. Pat. No. 5,486,832 to Hulderman employs millimeter wave radar and optical techniques to eliminate the need for a mechanical scanning system. A 35-degree arc is illuminated in the azimuth direction and 6 degrees in elevation. The reflected waves are separated into sixteen independent, simultaneously overlapping 1.8 degree beams. Each beam, therefore, covers a width of about 3 feet at 100 feet distance from the vehicle, which is far too large to form an image of the object in the field of view. As a result, it is not possible to identify the objects in the field of view. All that is known is that an object exists; also no attempt has been made to determine whether the object is located on the roadway or not, therefore this invention suffers from the limitations of other radar systems.
U.S. Pat. No. 5,504,482 to Schreder discloses an automobile equipped with an inertial and satellite navigation system as well as a local area digitized street map. The main use of this patent is for route guidance in the presence of traffic jams, etc. This patent describes how information as to the state of the traffic on a highway can be transmitted and utilized by a properly equipped vehicle to change the route the driver would take in going to his destination. Nevertheless, this patent provides a good picture of the state of the art as can be seen from the following quoted paragraphs:
xe2x80x9c . . . there exists a wide range of technologies that have disadvantageously not been applied in a comprehensive integrated manner to significantly improve route guidance, reduce pollution, improve vehicular control and increase safety associated with the common automobile experience. For example, it is known that gyro based inertial navigation systems have been used to generate three-dimensional position information, including exceedingly accurate acceleration and velocity information over a relatively short travel distance, and that GPS satellite positioning systems can provide three-dimensional vehicular positioning and epoch timing, with the inertial system being activated when satellite antenna reception is blocked during xe2x80x9cdrop outxe2x80x9d for continuous precise positioning. It is also known that digitized terrain maps can be electronically correlated to current vehicular transient positions, as have been applied to military styled transports and weapons. For another example, it is also known that digitally encoded information is well suited to RF radio transmission within specific transmission carrier bands, and that automobiles have been adapted to received AM radio, FM radio, and cellular telecommunication RP transmissions. For yet another example, it is further known that automobile electronic processing has been adapted to automatically control braking, steering, suspension and engine operation, for example, anti-lock braking, four-wheel directional steering, dynamic suspension stiffening during turns and high a speed, engine governors limiting vehicular speed, and cruise control for maintaining a desired velocity. For still another example, traffic monitors, such as road embedded magnetic traffic light sensor loops and road surface traffic flow meters have been used to detect traffic flow conditions. While these sensors, meters, elements, systems and controls have served limited specific purposes, the prior art has disadvantageously failed to integrate them in a comprehensive fashion to provide a complete dynamic route guidance, dynamic vehicular control, and safety improvement system.
xe2x80x9cRecently, certain experimental integrated vehicular dynamic guidance systems have been proposed. Motorola has disclosed an Intelligent Vehicle Highway System in block diagram form in copyright dated 1993 brochure. Delco Electronics has disclosed another Intelligent Vehicle Highway System also in block diagram form in Automotive News published on Apr. 12, 1993. These systems use compass technology for vehicular positioning. However, displacement wheel sensors are plagued by tire slippage, tire wear and are relatively inaccurate requiring recalibration of the current position. Compasses are inexpensive, but suffer from drifting particularly when driving on a straight road for extended periods. Compasses can sense turns, and the system may then be automatically recalibrated to the current position based upon sensing a turn and correlating that turn to the nearest turn on a digitized map, but such recalibration, is still prone to errors during excessive drifts. Moreover, digitized map systems with the compass and wheel sensor positioning methods operate in two dimensions on a three dimensional road terrain injecting further errors between the digitized map position and the current vehicular position due to a failure to sense distance traveled in the vertical dimension.
xe2x80x9cThese Intelligent Vehicle Highway Systems appear to use GPS satellite reception to enhance vehicular tracking on digitized road maps as part of a guidance and control system. These systems use GPS to determine when drift errors become excessive and to indicate that recalibration is necessary. However, the GPS reception is not used for automatic accurate recalibration of current vehicular positioning, even though C-MIGITS and like devices have been used for GPS positioning, inertial sensing and epoch time monitoring, which can provide accurate continuous positioning.
xe2x80x9cThese Intelligent Vehicle Highway Systems use the compass and wheel sensors for vehicular positioning for route guidance, but do not use accurate GPS and inertial route navigation and guidance and do not use inertial measuring units for dynamic vehicular control. Even though dynamic electronic vehicular control, for example, anti-lock braking, anti-skid steering, and electronic control suspension have been contemplated by others, these systems do not appear to functionally integrate these dynamic controls with an accurate inertial route guidance system having an inertial measuring unit well suited for dynamic motion sensing. There exists a need to further integrate and improve these guidance systems with dynamic vehicular control and with improved navigation in a more comprehensive system.
xe2x80x9cThese Intelligent Vehicle Highway Systems also use RP receivers to receive dynamic road condition information for dynamic route guidance, and contemplate infrastructure traffic monitoring, for example, a network for road magnetic sensing loops, and contemplate the RF broadcasting of dynamic traffic conditions for dynamic route guidance. The disclosed two-way RF communication through the use of a transceiver suggests a dedicated two-way RF radio data system. While two-way RF communication is possible, the flow of necessary information between the vehicles and central system appears to be exceedingly lopsided. The flow of information from the vehicles to a central traffic radio data control system may be far less than the required information from traffic radio data control system to the vehicles. It seems that the amount of broadcasted dynamic traffic flow information to the vehicles would be far greater than the information transmitted from the vehicles to the central traffic control center. For example, road side incident or accident emergency messages to a central system may occur far less than the occurrences of congested traffic points on a digitized map having a large number of road coordinate points.
xe2x80x9cConserving bandwidth capacity is an objective of RF communication systems. The utilization of existing infra structure telecommunications would seem cost-effective. ATandT has recently suggested improving the existing cellular communication network with high speed digital cellular communication capabilities. This would enable the use of cellular telecommunications for the purpose of transmitting digital information encoding the location of vehicular incidents and accidents. It then appears that a vehicular radio data system would be cost-effectively used for unidirectional broadcasting of traffic congestion information to the general traveling public, while using existing cellular telecommunication systems for transmitting emergency information. The communication system should be adapted for the expected volume of information. The Intelligent Vehicular Highway Systems disadvantageously suggest a required two-way RF radio data system. The vast amount of information that can be transmitted may tend to expand and completely occupy a dedicated frequency bandwidth. To the extent that any system is bidirectional in operation tends to disadvantageously require additional frequency bandwidth capacity and system complexity.xe2x80x9d
U.S. Pat. No. 5,506,584 to Boles relates to a system for communication between vehicles through a transmit and transponder relationship. The patent mentions that there may be as many as 90 vehicles within one half mile of an interrogation device in a multi-lane environment, where many of them may be at the same or nearly the same range. The Boles patent utilizes a transponder device, the coded responses which are randomized in time and an interrogation device which processes the return signals to provide vehicle identification speed, location and transponder status information on vehicles to an operator or for storage in memory. No mention is made of how a vehicle knows its location and therefore how it can transmit that location to other vehicles.
U.S. Pat. No. 5,530,447 to Henderson, et al. shows a system used to classify targets as threatening or non-threatening, depending on whether the target is moving relative to the ground. This system is only for vehicles in an adjacent lane and is primarily meant to protect against blind-spot type accidents. No estimation is made by the system of the position of the target vehicle or the threatening vehicle, only its relative velocity.
U.S. Pat. No. 5,530,651 to Uemura, et al. discloses a combination ultrasonic and laser radar optical detection system which has the feature that if the ability of the system to detect an obstacle decreases due to soiled lenses, rain, snow, etc., then the vehicle control system automatically limits the speed, for example, that the vehicle can travel in the adverse weather conditions. The speed of the vehicle is also reduced when the visibility ahead is reduced due to a blind, curved corner.
U.S. Pat. No. 5,540,298 to Yoshioka, et al. is primarily concerned with changing the suspension and steering characteristics of the vehicle in order to prevent unstable behavior of the vehicle in response to the need to exercise a collision avoidance maneuver. The collision anticipation system consists of an ultrasonic unit and two optical laser radar units.
U.S. Pat. No. 5,576,972 to Harrison provides a good background of how neural networks are used to identify various of objects. Although not directly related to intelligent transportation systems or o accident-avoidance systems such as described herein, these techniques will be applied to the invention described herein as discussed below.
U.S. Pat. No. 5,585,798 to Yoshioka, et al. uses a combination of a CCD camera and a laser radar unit. The invention attempts to make a judgement as to the danger of each of the many obstacles that are detected. The load on the central processor is monitored by looking at different obstacles with different frequencies depending on their danger to the present system. A similar arrangement is contemplated for the invention as disclosed herein.
U.S. Pat. No. 5,572,428 to Ishida is concerned with using a radar system plus a yawl rate sensor and a velocity sensor to determine whether a vehicle will collide with another vehicle based on the area occupied by each vehicle. Naturally, since radar cannot accurately determine this area it has to be assumed by the system.
U.S. Pat. No. 5,606,506 to Kyrtsos provides a good background of the GPS satellite system. It discloses a method for improving the accuracy of the GPS system using an inertial guidance system. This is based on the fact that the GPS signals used by Kyrtsos do not contain a differential correction and the selective access feature is on. Key paragraph from this application that is applicable to the instant invention follow.
xe2x80x9cSeveral national governments, including the United States 7, (U.S.) of America, are presently developing a terrestrial position determination system, referred to generically as a global positioning system (GPS). A GPS is a satellite-based radio-navigation system that is intended to provide highly accurate three-dimensional position information to receivers at or near the surface of the Earth.
xe2x80x9cThe U.S. government has designated its GPS the xe2x80x9cNAVSTAR.xe2x80x9d The NAVSTAR GPS is expected to be declared fully operational by the U.S. government in 1993. The government of the former Union of Soviet Socialist Republics (USSR) is engaged in the development of a GPS known as xe2x80x9cGLONASSxe2x80x9d. Further, two European systems known as xe2x80x9cNAVSTARxe2x80x9d and xe2x80x9cGRANASxe2x80x9d are also under development. For ease of discussion, the following disclosure focuses specifically on the NAVSTAR GPS. The invention, however, has equal applicability to other global positioning systems.
xe2x80x9cIn the NAVSTAR GPS, it is envisioned that four orbiting GPS satellites will exist in each of six separate circular orbits to yield a total of twenty-four GPS satellites. Of these, 3xe2x80x2 twenty-one will be operational and three will serve as spares. The satellite orbits will be neither polar nor equatorial but will lie in mutually orthogonal inclined planes.
xe2x80x9cEach GPS satellite will orbit the Earth approximately once every 12 hours. This coupled with the fact that the 4 Earth rotates on its axis once every twenty-four hours causes each satellite to complete exactly two orbits while the Earth turns one revolution.
xe2x80x9cThe position of each satellite at any given time will be Z precisely known and will be continuously transmitted to the Earth. This position information, which indicates the position of the satellite in space with respect to time (GPS time), is known as ephemeris data.
xe2x80x9cIn addition to the ephemeris data, the navigation signal 5 transmitted by each satellite includes a precise time at which the signal was transmitted. The distance or range from a receiver to each satellite may be determined using this time of transmission which is included in each navigation signal. By noting the time at which the signal was received at the receiver, a propagation time delay can be calculated. This time delay when multiplied by the speed of propagation of the signal will yield a xe2x80x9cpseudorangexe2x80x9d from the transmitting satellite to the receiver.
xe2x80x9cThe range is called a xe2x80x9cpseudorangexe2x80x9d because the receiver e clock may not be precisely synchronized to GPS time and because propagation through the atmosphere introduces delays into the navigation signal propagation times. These result, respectively, in a clock bias (error) and an atmospheric bias (error). Clock biases may be as large as several milliseconds.
xe2x80x9cUsing these two pieces of information (the ephemeris data and the pseudorange) from at least three satellites, the position of a receiver with respect to the center of the Earth can be determined using passive triangulation techniques.
xe2x80x9cTriangulation involves three steps. First, the position of at least three satellites in xe2x80x9cviewxe2x80x9d of the receiver must be determined. Second, the distance from the receiver to each satellite must be determined. Finally, the information from the first two steps is used to geometrically determine the position of the receiver with respect to the center of the Earth.
xe2x80x9cTriangulation, using at least three of the orbiting GPS satellites, allows the absolute terrestrial position (longitude, latitude, and altitude with respect to the Earth""s center) of any Earth receiver to be computed via simple geometric theory. The accuracy of the position estimate depends in part on the number of orbiting GPS satellites that are sampled. Using more GPS satellites in the computation can increase the accuracy of the terrestrial position estimate.
xe2x80x9cConventionally, four GPS satellites are sampled to determine each terrestrial position estimate. Three of the satellites are used for triangulation, and a fourth is added to correct for the clock bias described above. If the receiver""s clock were precisely synchronized with that of the GPS satellites, then this fourth satellite would not be necessary. However, precise (e.g., atomic) clocks are expensive and are, therefore, not suitable for all applications.
xe2x80x9cFor a more detailed discussion on the NAVSTAR GPS, see Parkinson, Bradford W. and Gilbert, Stephen W., xe2x80x9cNAVSTAR: Global Positioning Systemxe2x80x94Ten Years Later, xe2x80x9cProceedings of the IEEE, Vol. 71, No. 10, October 1983; and GPS: A Guide to the Next Utility, published by Trimble Navigation Ltd., Sunnyvale, Calif., 1989, pp. 147, both of which are incorporated herein by reference. For a detailed discussion of a vehicle positioning/navigation system which uses the NAVSTAR GPS, see commonly owned U.S. Pat. No. 5,555,503, entitled xe2x80x9cVehicle Position Determination System and Method,xe2x80x9d filed Dec. 3, 1990, which is incorporated herein by reference.
xe2x80x9cThe NAVSTAR GPS envisions two modes of modulation for the carrier wave using pseudorandom signals. In the first mode, the carrier is modulated by a xe2x80x9cC/A signalxe2x80x9d and is referred to as the xe2x80x9cCoarse/Acquisition modexe2x80x9d. The Coarse/Acquisition or C/A mode is also known as the xe2x80x9cStandard50 Positioning Servicexe2x80x9d. The second mode of modulation in the NAVSTAR GPS is commonly referred to as the xe2x80x9cprecisexe2x80x9d or xe2x80x9cprotectedxe2x80x9d (P) mode. The P-mode is also known as the xe2x80x9cPrecise Positioning Servicexe2x80x9d. The P-mode is intended for use only by Earth receivers specifically authorized by the United States government. Therefore, the P-mode sequences are held in secrecy and are not made publicly available. This forces most GPS users to rely solely on the data provided via the C/A mode of modulation (which results in a less accurate positioning system).
xe2x80x9cMoreover, the U.S. government (the operator of the NAVSTAR GPS) may at certain times introduce errors into the C/A mode GPS data being transmitted from the GPS satellites by changing clock and/or ephemeris parameters. That is, the U.S. government can selectively corrupt the GPS data. The ephemeris and/or the clock parameters for one or more satellites may be slightly or substantially modified. This is known as xe2x80x9cselective availabilityxe2x80x9d or simply SA. SA may be activated for a variety of reasons, such as national security.
xe2x80x9cWhen SA is activated, the U.S. government is still able to use the NAVSTAR GPS because the U.S. government has access to the P-mode modulation codes. The C/A mode data, however, may be rendered substantially less accurate.
xe2x80x9cIn addition to the clock error, the atmospheric error and errors from selective availability, other errors which affect GPS position computations include receiver noise, signal reflections, shading, and satellite path shifting (e.g., satellite wobble). These errors result in computation of incorrect pseudoranges and incorrect satellite positions. Incorrect pseudoranges and incorrect satellite positions, in turn, lead to a reduction in the precision of the position estimates computed by a vehicle positioning system.xe2x80x9d
U.S. Pat. No. 5,613,039 to Wang, et al. is a collision warning radar system utilizing a real time adaptive probabilistic neural network. Wang discloses that 60% of roadway collisions could be avoided if the operator of the vehicle was provided warning at least one-half second prior to a collision. The radar system used by Wang consists of two separate frequencies. The reflective radar signals are analyzed by a probabilistic neural network that provides an output signal indicative of the likelihood and threat of a collision with a particular object. The invention further includes a Fourier transform circuit that converts the digitized reflective signal from a time series to a frequency representation. It is important to note that in this case, as in the others above, true collision avoidance will not occur since, without a knowledge of the roadway, two vehicles can be approaching each other on a collision course, each following a curved lane on a highway and yet the risk of collision is minimal due to the fact that each vehicle remains in its lane. Thus, true collision avoidance cannot be obtained without an accurate knowledge of the road geometry.
U.S. Pat. No. 5,757,646 to Talbot, et al. illustrates the manner in which centimeter level accuracy on the fly in real time is obtained. It is accomplished by double differencing the code and carrier measurements from a pair of fixed and roving GPS receivers. This patent also presents and excellent discussion of the problem and of various prior solutions as in the following paragraphs:
xe2x80x9cWhen originally conceived, the global positioning system (GPS) that was made operational by the United States Government was not foreseen as being able to provide centimeter-level position accuracies. Such accuracies are now commonplace.
xe2x80x9cExtremely accurate GPS receivers depend on phase measurements of the radio carriers that they receive from various orbiting GPS satellites. Less accurate GPS receivers simply develop the pseudoranges to each visible satellite based on the time codes being sent. Within the granularity of a single time code, the carrier phase can be measured and used to compute range distance as a multiple of the fundamental carrier wavelength. GPS signal transmissions are on two synchronous, but separate carrier frequencies xe2x80x9cL1xe2x80x9d and xe2x80x9cL2xe2x80x9d, with wavelengths of nineteen and twenty-four centimeters, espectively. Thus within nineteen or twenty-four centimeters, the phase of the GPS carrier signal will change 360xc2x0.
xe2x80x9cHowever the numbs of whole cycle (360xc2x0) carrier phase shifts between a particular GPS satellite and the GPS receiver must be resolved. At the receiver, every cycle will appear the same. Therefore there is an xe2x80x9cinteger ambiguityxe2x80x9d. The computational resolution of the integer ambiguity has traditionally been an intensive arithmetic problem for the computers used to implement GPS receivers. The traditional approaches to such integer ambiguity resolution have prevented on-the-fly solution measurement updates for moving GPS receivers with centimeter accurate outputs. Very often such highly accurate GPS receivers have required long periods of motionlessness to produce a first and subsequent position fix.
xe2x80x9cThere are numerous prior art methods for resolving integer ambiguities. These include integer searches, multiple antennas, multiple GPS observables, motion-based approaches, and external aiding. Search techniques often require significant computation time and are vulnerable to erroneous solutions or when only a few satellites are visible. More antennas can improve reliability considerably. If carried to an extreme, a phased array of antennas results whereby the integers are completely unambiguous and searching is unnecessary. But for economy the minimum number of antennas required to quickly and unambiguously resolve the integers, even in the presence of noise, is preferred.
xe2x80x9cOne method for integer resolution is to make use of the other observables that modulate a GPS timer. The pseudo-random code can be used as a coarse indicator of differential range, although it is very susceptible to multipath problems. Differentiating the L1 and L2 carriers provides a longer effective wavelength, and reduces the search space. However dual frequency receivers are expensive because they are more complicated. Motion-based integer resolution methods make use of additional information provided by platform or satellite motion. But such motion may not always be present when it is needed.xe2x80x9d
This system is used in an industrial environment where the four antennas are relatively close to each other. Practicing the teachings of this invention permits a navigational computer to solve for the position of the rover to within a few centimeters on the fly ten times a second. An example is given where the rover is an airplane.
U.S. Pat. No. 5,767,953 to McEwan describes a laser tape measure for measuring distance. It is distinct from laser radars in that the width of the pulse is measured in sub-nanosecond times, whereas laser radars are typically in the microsecond range. The use of this technology in the current invention would permit a much higher scanning rate than by convention radar systems and thus provide the opportunity for obtaining an image of the obstructions on the highway. It is also less likely that multiple vehicles having the same system would interfere with each other. For example, if we wish to scan an area 20 feet by 5 feet with a 0.2 inch pixel size, this would give on the order of one million pixels. If using laser radar, one pixel per microsecond is sent out, it would take one second to scan the entire area during which time the vehicle has traveled 88 feet at 60 miles an hour. On the other hand, if scanning this array at 100 feet, it would take 200 nanoseconds for the light to travel to the obstacle and back. Therefore, if a pulse is sent out every fifth of a microsecond, it will take a fifth of a second to obtain a million pixels, during which time the vehicle has traveled about 17 feet. If 250,000 pixels are used, the vehicle will only have traveled 4 feet.
U.S. Pat. No. 5,361,070 to McEwan, although describing a motion detector, discloses technology which is used as part of a system to permit a vehicle to precisely know where it is on the face of the earth at particular locations. The ultra wideband 200 picosecond radar pulse emitted by the low power radar device of this invention is inherently a spread spectrum pulse which generally spans hundreds of megahertz to several gigahertz. A frequency allocation by the FCC is not relevant. Furthermore, many of these devices may be co-located without interference. The concept of this device is actually disclosed in various forms in the following related patents to McEwan. The following comments will apply to this group of patents as a group, all of which are incorporated herein by reference.
U.S. Pat. No. 5,510,802 to McEwan discloses a time of light radio location system similar to what is described below. In this case, however, a single transmitter sends out a pulse, which is received by three receivers to provide sub-millimeter resolution. The range of this device is less than 10 feet.
The concept disclosed in McEwan""s U.S. Pat. No. 5,519,400 is that the MIR signal can be modulated with a coded sequence to permit positive identification of the sending device. In an additional McEwan patent, U.S. Pat. No. 5,589,838, a short-range radio location system is described. Additionally, in U.S. Pat. No. 5,774,091, McEwan claims that the MIR system will operate to 20 feet and give resolutions on the order of 0.01 inches.
Looking now at some of the relevant non-patent prior art:
Work has been done at JPL to develop a target recognition system. Neural networks pay a key role in that target recognition process. The recognition of vehicles on a roadway is a considerably simpler process. Through range gating, most of the cluttering information can be eliminated. The three-dimensional image obtained as described below will permit simple rotations of the image to artificially create a frontal view of the object being investigated. Also, the targets of interest here are considerably closer than was considered by JPL. Nevertheless, the techniques described in this reference and in the references cited by this reference, all of which are included in here by reference, are applicable here in a simplified form. The JPL study achieved over a 90% success rate at 60 frames per minute.
Significant additional improvement can be obtained for the WAAS system using the techniques described in the paper xe2x80x9cIncorporation of orbital dynamics to improve wide-area differential GPSxe2x80x9d by J. Ceva, W. Bertinger, R. Mullerschoen, T. Yunck and B. Parkinson, Institute of Navigation meeting on GPS technology, Palm Springs, Calif., September 1995), which is included herein by reference.
The ALVINN project of Carnegie Mellon University (Jochem, Todd M., Pomerlean, Dean A., and Thorpe, Charles E. xe2x80x9cVision-Based Neural Network Road and Intersection Detection and Traversal, xe2x80x9cIEEE Conference on Intelligent Robots and Systems, Aug. 5-9, 1995, Pittsburgh, Pa., USA) describes an autonomous land vehicle using a neural network. The neural network is trained based on how a driver drives the vehicle given the output from a video camera. The output of the neural network is the direction that the vehicle should head based on the input information from the video camera and the training based on what a good driver would have done. Such a system can be used in the present invention to guide a vehicle to a safe stop in the event that the driver becomes incapacitated or some other emergency situation occurs wherein the driver is unable to control the vehicle. The input to the neural network in this case would be the map information rather than a video camera. Additionally, the laser radar imaging system could also be an input to the system. This neural network system could also take over in the event that an accident becomes inevitable.
The DGPS correction information can be broadcast over the radio data system (RDS) via FM transmitters for land use. A company called Differential Correction, Inc. has come up with a technique to transmit this DGPS information on the RDS channel. This technique has been used in Europe since 1994 and in particular, Sweden has launched a nationwide DPGS service via the RDS (see, Sjoberg, Lars, xe2x80x9cA xe2x80x981 Meterxe2x80x99 Satellite Based Navigation Solutions for the Mobile Environment That Already Are Available Throughout Europexe2x80x9d). This system has the potential of providing accuracies on the premium service of between 1 and 2 meters. A 1 meter accuracy, coupled with the carrier phase system to be described below, provides an accuracy substantially better than 1 meter as required by the Road to Zero Fatalities (RtZF(trademark)(trademark)) system of this invention.
In addition to the FM RDS system, the following other systems can be used to broadcast DGPS correction data: cellular mobile phones, satellite mobile phones, MCA (multi-channel access), wireless tele-terminals, DARCs/RBDS (radio data systems/radio broadcast data system), type FM sub-carrier, exclusive wireless, and pagers. In particular, DARC type is used for vehicle information and communication systems so that its hardware can be shared. Alternately, the cellular phone system, coupled with the Internet, could be used for transmitting corrections (see, Ito, Toru and Nishiguchi, Hiroshi entitled xe2x80x9cDevelopment of DGPS using FM Sub-Carrier For ITSxe2x80x9d) with the exception of the Internet comment.
One approach for the cellular system is to use the GSM mobile telephone system, which is the Europe-wide standard. This can be used for transmitting DGPS and possibly map update information (see, Hob, A., Ilg, J. and Hampel, A. entitled xe2x80x9cIntegration Potential Of Traffic Telematics).
A paper by Amamoto, Naohiro and Matsumoto, Koji entitled xe2x80x9cObstruction Detector By Environmental Adaptive Background Image Updatingxe2x80x9d describes a method of distinguishing between moving object pixels, stationary object pixels, and pixels that change due to illumination changes in a video image. This paper appears to handle the case of a camera fixed relative to the earth, not one mounted on a vehicle. This allows the system to distinguish between a congested area and an area where cars are moving freely. The video sampling rate was 100 milliseconds.
A paper by Miyata, Yasuhiro and Otomo, Katsuya, Kato, Haijime, Imacho, Nobuhiro, Murata, Shigeo, entitled xe2x80x9cDevelopment Of Road Icing Prediction Systemxe2x80x9d describes a method of predicting road icing conditions several hours in advance based on an optical fiber sensor laid underneath the road and the weather forecast data of that area.
There is likely a better way of determining ice on the road than described in this paper. The reflection of an infrared off the road has to vary significantly depending on whether there is ice on the road or snow, or the road is wet or dry. An unsupervised neural network could be a better solution. The system of this paper measures the road surface temperature, air temperature and solar radiation. A combination of active and passive infrared would probably be sufficient. Perhaps a specially designed reflective surface could be used on the road surface in an area where it is not going to be affected by traffic.
What this paper showed is that if the proper algorithm is used, the actual road temperature can be predicted without the need to measure the temperature on the road. This implies that icing conditions can be predicted and the sensors would not be necessary. Once again, perhaps a neural network algorithm that monitors a particular section of road and compares it to the forecasted data would be all that is required. In other words, given certain meteorological data, the neural network ought to be able to determine that the probability is of icing. What is needed, therefore, is to pick a section of roadway and monitor that roadway with a state-owned vehicle throughout the time period when icing is likely to occur and determine if icing has occurred and compare that with the meteorological data using a neural network that is adapted for each section of road.
A paper by Min, Joon, Cho, Hyang, and Choi, Jong, entitled xe2x80x9cA Learning Algorithm Using Parallel Neuron Modelxe2x80x9d describes a method of accurately categorizing vehicles based on the loop in the highway. This system uses a form of neural network, but not a back propagation neural network. This would essentially be categorizing a vehicle by its magnetic signature. Much information is lost in this system because of the lack of knowledge of the vehicle""s velocity.
A paper by Doi, Ayumu, Yamamomo, Yasunori,and Butsuen, Tetsuro entitled xe2x80x9cDevelopment Of Collision Warning System And Its Collision Avoidance Effectxe2x80x9d describes a collision warning system that has twice the accuracy of conventional systems. It uses scanning laser radar. In the system described in this paper, the authors do not appear to use range gating to separate one vehicle from another.
In Choi, Jong and Kim, Hoi, xe2x80x9cAn Interim Report: Building A Wireless Internet-Based Traveler""s Information System As A Replacement Of Car Navigation Systemsxe2x80x9d, a system of showing congestion at intersections is broadcast to the vehicle through the Internet. The use of satellites is disclosed as well as VCS system.
Another example of the use of the Internet to provide highway users with up-to-date traffic congestion information. Nowhere in this example, is the Internet used to transmit map information.
A paper by Sheu, Dennis, Liaw, Jeff and Oshizawa, Al, entitled xe2x80x9cA Communication System For In-Vehicle Navigation Systemxe2x80x9d provides another description of the use of the Internet for real traffic information. However, the author unnecessarily complicates matters by using push technology which isn""t necessary and with the belief that the Internet connection would have to be stopped which, of course, is not the case. For example, looking at the @home network where everyone on the network is connected all the time.
Consider placing a requirement that all vehicles have passive transponders. This could be part of the registration system for the vehicle and, in fact, could even be part of the license plate. This is somewhat disclosed in a paper by Shladover, Steven entitled xe2x80x9cCooperative Advanced Vehicle Control and Safety Systems (AVCSS)xe2x80x9d. This paper discusses advanced vehicle control and safety systems (AVCSS). AVCSS sensors will make it easy to detect the presence, location and identity of all other vehicles in their vicinity. Passive radio frequency transponders are disclosed. The use of differential GPS with accuracies as good as about two (2) centimeters, coupled with an inertial guidance system, is disclosed, as is the ability of vehicles to communicate their locations to other vehicles. It discloses the use of accurate maps, but not of lateral vehicle control using these maps. It is obvious from reading this paper that the author did not contemplate the safety system aspects of using accurate maps and accurate GPS. In fact, the author stresses the importance of cooperation between various government levels and agencies and the private sector in order to make AVCSS feasible. xe2x80x9cAutomotive suppliers cannot sell infrastructure -dependent systems to their customers until the very large majority of the infrastructure is suitable equipped.xe2x80x9d
A paper by Rick Schuman entitled xe2x80x9cProgress Towards Implementing Interoperable DSRC Systems In North Americaxe2x80x9d describes the standards for dedicated short-range communications (DSRC). DSRC could be used for inter-vehicle communications, however, its range according to the ITS proposal to the Federal Government would be limited to about 90 meters. Also, there may be a problem with interference from toll collection systems, etc. According to this reference, however, xe2x80x9cit is likely that any widespread deployment of intersection collision avoidance or automated highways would utilize DSRCxe2x80x9d. DSRC physical layer uses microwaves in the 902 to 928 megahertz band. However, ITS America submitted a petition to the FCC seeking to use the 5.85 to 5.925 gigahertz band for DSRC applications.
It is pointed out that when the operator begins operating his vehicle, he will not be near a reference point as determined by the MIR locator system. In this situation, he will use the standard GPS system with the WAAS corrections. This will provide accuracy of a few meters. This accuracy might be improved as he travels down the road through map-matching. The vehicle will know, however, that is not operating in the super accurate mode. As soon as the vehicle passes and MRI system, it will then be able to calculate exactly where it is within centimeters and the vehicle will know that it is in the accurate mode. Naturally, any travel on a controlled highway would require frequent MRI stations and the vehicle can be accurately contained within its proper corridors. Also, the size of the corridors that the vehicle is permitted in can be a function of the accuracy state of the vehicle.
A paper by O""Shea, Michael and Shuman, Valerie entitled xe2x80x9cLooking Ahead: Map Databases in Predictive Positioning and Safety Systems discusses map databases which can assist radar and image-processing systems of this invention since the equipped vehicle would know where the road ahead is and can therefore distinguish the lane that the preceding vehicle is in. No mention, however, is made in this reference of how this is accomplished through range gating. This reference also mentions that within five years it may be possible to provide real time vehicle location information of one meter accuracy. However, it mentions that this will be limited to control access roads such as interstate highways. In other words, the general use of this information on all kinds of roads for safety purposes is not contemplated. This reference also states that xe2x80x9croad geometry, for example, may have to be accurate to within one meter or less as compared to the best available accuracy of 15 meters todayxe2x80x9d. This reference also mentions the information about lane configuration that can be part of the database including the width of each lane, the number of lanes, etc. and that this can be used to determine driver drowsiness. This reference also states that xe2x80x9cat normal vehicle speeds, the vehicle location must be updated every few milliseconds. It is also stated that the combination of radar and map data can also help to interpret radar information such as the situation where a radar system describes an overpass as a semi truck . . . xe2x80x9d Image processing in this Reference is limited to assessing road conditions such as rain, snow, etc. The use of a laser radar system is not contemplated by this reference. The use of this information for road departures warnings is also mentioned, as is lane following. The Reference also mentions that feedback from vehicles can be used to improve map configurations.
A paper entitled xe2x80x9cPrecursor Systems Analyses of Automated Highway Systems (Executive Summary)xe2x80x9d discloses that xe2x80x9can AHS (automated highway system) can double or triple the efficiency of today""s most congested lanes while significantly increasing safety and trip qualityxe2x80x9d.
A paper entitled xe2x80x9cIntelligent Transportation Infrastructure Benefits: Expected And Experiencedxe2x80x9d provides a summary of costs and benefits associated with very modest ITS implementations. Although a complete cost benefit analysis has not been conducted on the instant invention, it is evident from reading this reference that the benefits to cost reference will be a very large number.
According to this paper the congestion in the United States is increasing at about 9% per year. In 50 metropolitan areas the cost in 1992 was estimated at 48 billion dollars and in Washington, DC it represented an annual cost of $822 per person, or $1,580 per registered vehicle. In 1993, there were 40,115 people killed and 3 million injured in traffic accidents. Sixty-one percent (61%) of all fatal accidents occurred in rural areas. This reference lists the 29 user services that make up the ITS program. It is interesting that the instant invention provides 24 of the 29 listed user services.
This reference further goes into considerable discussion on various means of communication between a vehicle and other vehicles as well as the infrastructure. However, no recommendations are made for vehicle-to-vehicle communication technologies.
A version of CDPD, which is a commercially available mobile, wireless data network operated in the packet-switching mode, extends Internet protocol capabilities to cellular channels. This is reported on in a paper entitled xe2x80x9cIntelligent Transportation Systems (ITS) Opportunityxe2x80x9d.
According to a paper by Kelly, Robert, Povich, Doublas and Poole, Katherine entitled xe2x80x9cPetition of Intelligent Transportation Society of America for Amendment Of The Commission""s Rules to Add Intelligent Transportation Services (ITS) As A New Mobile Service With Co-Primary Status In The 5.850 To 5.925 GHzxe2x80x9d, from 1989 to 1993, police received an annual average of over 6.25 million vehicle accident reports. During this same period the total comprehensive cost to the nation of motor vehicle accidents exceeded the annual average of 400 billion dollars. In 1987 alone Americans lost over 2 billion hours (approximately 22,800 years) sitting in traffic jams. Each driver in Washington D.C. wastes an average of 70 hours per year idling in traffic. Since 1986 car travel has increased almost 40%xe2x80x94that""s in 10 years, which amounts to about a 3.4% increase per year.
Further, from Kelly et al., the FCC has allocated in Docket 94-124, 46.7 to 46.9 GHz and 76 to 77 GHz bands for unlicensed vehicular collision avoidance radar. The petition for DSRC calls for a range of up to 50 meters. This would not be sufficient for the RtZF(trademark) system. For example, take the case of a car passing another car at 150 kilometers per hour. Fifty meters amounts to about one second, which would be insufficient time for the passing vehicle to complete the passing and return to the safe lane. Something more in the order of 500 meters would be more appropriate. This, however, may interfere with other uses of DSRC such as automatic toll taking, etc., thus DSRC may not be the optimum communication system for communication between vehicles. DSRC is expected to operate at a data rate of approximately 600 kbps. DSRC is expected to use channels that are six megahertz wide. It might be possible to allocate one or more of the six megahertz channels to RtZF(trademark).
On DSRC Executive Roundtablexe2x80x94Meeting Summary, Appendix Ixe2x80x94Proposed Changes to FCC Regulations covering the proposed changes to the FCC regulations, it is stated that xe2x80x9c . . . DSRCS systems utilize non-voice radio techniques to transfer data over short distances between roadside and mobile units, between mobile units and between portable and mobile units to perform operations related to the improvement of traffic flow, traffic safety and other intelligent transportation service applications . . . xe2x80x9d, etc.
There are one million, sixty-nine thousand, twenty-two miles of paved non-local roads in the US. Eight hundred twenty-one thousand and four miles of these are classified as xe2x80x9cruralxe2x80x9d and the remaining two hundred forty-eight thousand, eighteen miles are xe2x80x9curbanxe2x80x9d.
The existing interstate freeway system consists of approximately 50,000 miles which is 1% of the 3.8 million miles of roads. Freeways make up 3% of the total urban/suburban arterial mileage and carry approximately 30% of the total traffic.
In one study, dynamic route guidance systems were targeting at reducing travel time of the users by 4%. Under the system of this invention, the travel times would all be known and independent of congestion once a vehicle had entered the system. Under the other system, the dynamic delays can change measurably after a vehicle is committed to a specific route. According to the Federal Highway Administration Intelligent Transportation Systems (ITS Field Operational Test), dynamic route guidance systems have not been successful.
There are several systems presented in the Federal Highway Administration Intelligent Transportation Systems (ITS Field Operational Test) for giving traffic information through commuters, called xe2x80x9cAdvance Traveler Information Systemxe2x80x9d (ATIS). In none of these articles does it discuss the variation in travel time during rush hour for example, from one day to the next. The variability in this travel time would have to be significant to justify such a system. Naturally a system of this type would be unnecessary in situations where the instant invention has been deployed. The single most important cause of variability from day to day would be traffic incidents such as accidents, which are eliminated in the instant invention. One of the conclusions in a study published in the Federal Highway Administration Intelligent Transportation Systems (ITS Field Operational Test) titled xe2x80x9cDirect Information Radio using Experimental Communication Technologiesxe2x80x9d was that drivers did not feel that the system was a significant over commercial radio traffic information. They did think the system was an improvement over television traffic information and changeable message signs. The drivers surveyed on average having changed their route only one time in the eight week test period due to information they received from the system.
A paper by Han, Shaowei entitled Ambiguity Recovery For Long-Range GPS Kinematic Positioning appears to say that if a mobile receiver is initially synchronized with a fixed receiver such that there is no integer ambiguity, and if the mobile receiver then travels away from the fixed receiver, and during the process it loses contact with the satellites for a period of up to five minutes, that the carrier phase ambiguity can be recovered or eliminated, providing again centimeter-type accuracies. Presumably the fixed station is providing the differential corrections.
A great flow of commercially available data will begin with the new generation of high resolution (as fine as 1 meter) commercial earth imaging satellites from companies like EarthWatch and SPOT Image. Sophisticated imaging software is being put in place to automatically process these imaging streams into useful data products.
The map database of the instant invention will conform to the open GIS specification. This will permit such devices to obtain on-line consumer information services such as driving advisories, digital yellow pages that give directions, local weather pictures and forecasts and video games that display local terrain.
Singh, Daljit and Grewal, Harkirat, xe2x80x9cAutonomous Vehicle using WADGPSxe2x80x9d discussed ground vehicle automation using wide-area DGPS. Though this reference describes many of the features of the present invention, it does not disclose sub-meter accuracy or sub-meter accurate mapping.
O""Connor, Michael, Bell, Thomas, Elkaim, Gabriel and Parkinson, Bradford, xe2x80x9cAutomatic Steering of Farm Vehicles Using GPSxe2x80x9d describes an automatic steering system for farm vehicles where the vehicle lateral position error never deviated by more than 10 centimeters, using a carrier phase differential GPS system whereby the differential station was nearby.
Pullen, Samuel, Enge, Per and Parkinson, Bradford, xe2x80x9cSimulation-Based Evaluation of WAAS Performance: Risk and Integrity Factorsxe2x80x9d discusses the accuracy that can be expected from the WAAS system. This paper indicates that the standard deviation for WAAS is approximately 1 meter. To get more accurate results requires more closely spaced differential stations. Using DGPS stations within 1,500 kilometer from the vehicle, high accuracy receivers can within 3 meters accuracy for DGPS.
J. Wu and S. G. Lin, xe2x80x9cKinematic Positioning with GPS Carrier Pahses by Two Types of Wide Laningxe2x80x9d, Journal of the Institute of Navigation, Vol. 44, No. 4, Winter 1997-1998 the solution of the integer ambiguity problem can be simplified by performing other constructs other than the difference between the two phases. One example is to use three times one phase angle, subtracted from four times another phase angle. This gives a wavelength of 162.8 centimeters vs. 86.2 for the single difference. Preliminary results with a 20-kilometer base line show a success rate as high as 95% for centimeter level accuracies.
J. F. Zunberge, M. M. Watkins and F. H. Webb, xe2x80x9cCharacteristics and Applications of Precise GPS Clock Solutions Every 30 Secondsxe2x80x9d, Journal of the Institute of Navigation, Vol. 44, No. 4, Winter 1997-1998. It appears that using the techniques described in this reference that the WAAS system could eventually be improved to provide accuracies in the sub-decimeter range for moving vehicles without the need for differential GDPS even with selective access on. This data would be provided every 30 seconds.
The clock dithering aspect of SA results in GPS satellite clock errors that vary by 24 meters RMS over time scales longer than a few hundred seconds. The solution of this reference may require that an accurate clock be based in the vehicle.
R. Braff, xe2x80x9cDescription of the FAA""s Local Area Augmentation System (LAAS)xe2x80x9d, Journal of the Institute of Navigation, Vol. 44, No. 4, Winter 1997-1998. The LAAS System is the FAA""s ground-based augmentation system for local area differential GPS. It is based on providing corrections of errors that are common to both ground-based and aircraft receivers. These corrections are transmitted to the user receivers via very high frequency VHF, line of sight radio broadcast. LAAS has the capability of providing accuracy on the order of 1 meter or better on the final approach segment and through rollout. LAAS broadcasts navigational information in a localized service volume within approximately 30 nautical miles of the LAAS ground segment.
W. I. Bertiger et al., xe2x80x9cA Real-Time Wide Area Differential GPS Systemxe2x80x9d, Journal of the Institute of Navigation, Vol. 44, No. 4, Winter 1997-1998. This paper describes the software that is to be used with the WAAS System. The WAAS System is to be completed by the year 2001. The goal of the research described in this paper is to achieve sub-decimeter accuracies worldwide, effectively equaling local area DGPS performance worldwide. The full computation done on a Windows NT computer adds only about 3 milliseconds. The positioning accuracy is approximately 25 centimeters in the horizontal direction. That is the RMS value so that gives an error at xc2x13 sigma of 1.5 meters. Thus, the real time wide area differential GPS system is not sufficiently accurate for the purposes of this invention.
Y. M. Al-Haifi et al., xe2x80x9cPerformance Evaluation of GPS Single-Epoch On-theFly Ambiguity Resolutionxe2x80x9d, Journal of the Institute of Navigation, Vol. 44, No. 4, Winter 1997-1998. xe2x80x9cPerformance evaluation of GPS single epoch on the fly ambiguity resolution.xe2x80x9d This technique demonstrates sub-centimeter precision results all of the time provided that at least five satellites are available and multipath errors are small. A resolution of 0.001 cycles is not at all unusual for geodetic GPS receivers. This leads to a resolution on the order of 0.2 millimeters. In practice, multipath affects, usually from nearby surfaces, limit the accuracy achievable to around 5 millimeters. It is currently the case that the reference receiver can be located within a few kilometers of the mobile receiver. In this case most of the other GPS error sources are common. The only major problem, which needs to be solved to carry out high precision kinematic GPS, is the integer ambiguity problem. This is because at any given instant the whole number of cycles between the satellite and the receiver is unknown. The recovery of the unknown whole wavelengths or integer ambiguities is therefore of great importance to precise phase positioning. Recently, a large amount of research has focused on so called on the fly (OTF) ambiguity resolution methodologies in which the integer ambiguities are solved for while the unknown receiver is in motion.
The half second processing time required for Y. M. Al-Haifi et al. represents 44 feet of motion which would be intolerable. The basic guidance system in this case would have to be the laser gyro on the vehicle. With faster PC, one-tenth a second processing time would be achievable, corresponding to approximately 10 feet of motion of the vehicle, putting less reliance on the laser gyroscope. Nowhere in Y. M. Al-Haifi et al. is the use of this system on automobiles suggested. The technique presented in this paper is a single epoch basis (OTF) ambiguity resolution procedure that is insensitive to cycle slips. This system requires the use of five or more satellites which suggests that additional GPS satellites may be launched to make the smart highway system more accurate.
Al Gore, xe2x80x9cThe Digital Earth:Understanding our Planet in the 21st Centuryxe2x80x9d, California Science Center, Jan. 31, 1998. The Administration has licensed commercial satellites that will provide one meter resolution imaging beginning in 1998. Such imaging can be combined with digital highway maps to provide an accuracy and reality check.
F. van Diggelen, xe2x80x9cGPS and GPS+GLONASS RTKxe2x80x9d, ION-GPS, September 1997 xe2x80x9cNew Products Descriptionsxe2x80x9d gives a good background of real time kinematic systems using the carrier frequency. The products described in this paper illustrate the availability of centimeter level accuracies for the purposes of the RtZF(trademark) system. The product described in F. van Diggelen requires a base station that is no further than 20 kilometers away.
R. C. Hayward et al., xe2x80x9cInertially Aided GPS Based Attitude Heading Reference System (AHRS) for General Aviation Aircraftxe2x80x9d provides the list of a series of inertial sensors.
S. Malys et al., xe2x80x9cThe GPS Accuracy Improvement Initiativexe2x80x9d provides a good discussion of the errors inherent in the GPS system without using differential corrections. It is there reported that the standard GPS provides a 9 meter RMS 3-D navigational accuracy to authorize precise positioning service users. The PPS clock states are those which are free of the effects of selective availability. This reference indicates that there are improvements planned in the GPS system that will further enhance its accuracy, at least for PPS users. The accuracies of these satellites independently of the accuracies of receiving units is expected to be between 1 and 1.5 meters RMS. Over the past eight years of GPS operations, a 50% (4.6 meter to 2.3 meter) PPS performance improvement has been observed for the signal in space range errors. This, of course, is the RMS error. The enhancements contained in the accuracy improvement initiative will provide another incremental improvement from the current 2.3 meters to 1.3 meters and perhaps to as low as 40 centimeters.
K. Ghassemi et al., xe2x80x9cPerformance Projections of GPS IIFxe2x80x9d describes the performance objectives for a new class of GPS 2F satellites to be launched in late 2001.
Previous inventions have attempted to solve the collision avoidance problem for each vehicle independently of the other vehicles on the roadway. Systems that predict vehicle trajectories fail because two vehicles can be on a collision course and within the last 0.1 second a slight change of direction avoids the collision. This is a common occurrence that depends on the actions of the individual drivers and no collision avoidance system now in existence can differentiate this case from an actual collision. In the present invention, every equipped vehicle will be confined to a corridor and to a position within that corridor where the corridor depends on sub-meter accurate digital maps. Only if that vehicle deviates from the corridor will an alarm sound or the vehicle control system take over control of the vehicle sufficiently to prevent the vehicle from leaving its corridor if an accident would result from the departure from that corridor.
Additionally, no prior art system has successfully used the GPS navigational system, or an augmented DGPS to locate a vehicle on a roadway with sufficient accuracy that that information can be used to prevent the equipped vehicle from leaving the roadway or striking another similarly equipped vehicle.
Prior art systems in addition to being poor at locating potential hazards on the roadway, have not been able to ascertain whether they are in fact on the roadway of off on the side, whether they are threatening vehicles, static signs over overpasses etc. In fact no credible attempt to date has been made to identify or categorize objects which may impact the subject vehicle.
The first phase of this invention can be practiced with only minor retrofit type additions to the vehicle. These include the addition of a differential GPS system and an accurate map database. In this first phase the driver will only be warned when he or she is about to depart from the road surface. During the second phase of practicing this invention, the earning system will be augmented with a system which will prevent the operator from leaving the assigned corridor and in particular leaving the road at high speed. In further phases of the implementation of this invention, additional systems will be integrated which will scan the roadway and act to prevent accidents with vehicles that do not have the system installed. Also communication systems will be added to permit the subject vehicle to communicate its position, velocity etc. to other nearby vehicles which are also equipped with a system.
A primary preferred embodiment of the system, therefore, is to equip a vehicle with a DGPS system, an laser gyro inertial guidance system, vehicle steering and brake control apparatus, a sub-meter accurate digital map system with the relevant maps, a scanning sub-nanosecond pulsed infrared laser radar, a system for sensing or receiving signals from a highway based precise position determination system, and communications systems for (1) sending and receiving data from similarly equipped vehicles, (2) receiving updated maps and map status information, and (3) receiving weather and road condition information. A preferred embodiment for the infrastructure enhancements includes a DGPS system, a micropower impulse radar precise position determining system and local weather and road condition determination and transmission system.
This invention is a method and apparatus for preventing vehicle accidents. A vehicle is equipped with a differential GPS (DGPS) navigational system as well as an inertial navigation subsystem. Part of the system can be an array of infrastructure stations that permit the vehicle to exactly determine its position at various points along its path. Such stations would typically be located at intervals such as every 50 miles along the roadway, or more or less frequently depending on requirements as described below. These stations permit the vehicle to become its own DGPS station and thus to correct for the GPS errors and to set the position of the vehicle based initial guidance system. It also provides sufficient information for the vehicle to use the carrier frequency to determine its absolute position to within less than a meter. Data is also available to the vehicle that provides information as to the edges of the roadway at the location of the vehicle so that the vehicle control system can continuously determine its location relative to the roadway edges. In the initial implementation, the operator operates his or her vehicle and is unaware of the presence of the accident avoidance system. If, however, the operator falls asleep or for some other reason attempts to run off of the roadway at high speed, the system will detect that the vehicle is approaching an edge of the roadway and will either sound an alarm or prevent the vehicle from leaving the roadway when doing so would lead to an accident. In some cases the system will automatically reduce the speed of the vehicle and stop it on the shoulder of the roadway.
It is important to note that the invention as described in the above paragraph is in itself a significant improvement to automotive safety. Approximately half of all fatal accidents involve only a single vehicle that typically leaves the roadway and impacts with a roadside obstacle. This typically happens when the driver in under the influence of alcohol or drugs, has a medical emergency or simply falls asleep. If this cause of accidents could be eliminated, the potential exists for saving many thousands of deaths per year when all vehicles are equipped with the system of this invention. This would make this the single greatest advance in automotive safety surpassing both seatbelts and airbags in lifesaving potential.
A first improvement to the basic invention is to provide the vehicle with a means using radar, lidar, optical or infrared imaging, or a similar technology, to determine the presence, location and velocity of other vehicles on the roadway which are not equipped with the accident avoidance system. The accident avoidance system (RtZF(trademark)) of this invention will not be able to avoid all accidents with such vehicles for the reasons discussed above, but will be able to provide the level of protection at least equal to the prior art systems. Some improvement over prior art systems will result from the fact that the equipped vehicle knows the location of the roadway edges, as well as the lane boundaries, not only at the location of the equipped vehicle but also at the location of the other nearby vehicles. Thus, the equipped vehicle will be able to determine that an adjacent vehicle has already left its corridor and warn the driver or initiate evasive action. In prior art systems, the location of the roadway is not known leading to significantly less discrimination ability.
A second improvement to the RtZF(trademark) of this invention is to provide communication ability to other nearby similarly equipped vehicles permitting the continuous transmission and reception of the locations of all equipped vehicles in the vicinity. With each vehicle knowing the location, and thus the velocity, of all potential impacting vehicles which are equipped with the RtZF(trademark), collisions between vehicles can be reduced and eventually nearly eliminated when all vehicles are equipped with the RtZF(trademark).
A third improvement comprises the addition of software to the system that permits vehicles on especially designated vehicle corridors for the operator to relinquish control of the vehicle to the vehicle based system, and perhaps to a roadway computer system. This then permits vehicles to travel at high speeds in a close packed formation thereby substantially increasing the flow rate of vehicles on a given roadway. Naturally, in order to enter the designated corridors, a vehicle would be required to be equipped with the RtZF(trademark). Similarly, this then provides an incentive to vehicle owners to have their vehicles so equipped so that they can enter the controlled corridors and thereby shorten their travel time.
Prior art systems require expensive modifications to highways to permit such controlled high speed close packed travel. Such modifications also require a substantial infrastructure to support the system. The RtZF(trademark) of the present invention, in its simplest form, does not require any modification to the roadway but rather relies primarily on the GPS or similar satellite system. The edge and lane boundary information is either present within the vehicle RtZF(trademark) memory or transmitted to the vehicle as it travels along the road. The permitted speed of travel is also communicated to the vehicles on the restricted corridor and thus each vehicle travels at the appointed speed. Since each vehicle knows the location of all other vehicles in the vicinity, should one vehicle slow down, due to an engine malfunction, for example, appropriate action can be taken to avoid an accident. Vehicles do not need to travel in groups as suggested and required by some prior art systems. Rather, each vehicle may independently enter the corridor and travel at the system defined speed until it leaves.
Another improvement involves the transmission of additional data concerning weather conditions, traffic accidents etc. to the equipped vehicle so that the speed of that vehicle can be limited to a safe speed depending on road conditions, for example. If moisture is present on the roadway and the temperature is dropping to the point that ice might be building up on the road surface, the vehicle can be notified by the roadway information system and prevented from traveling at an unsafe speed.
Principle objectives and advantages of the RtZF(trademark) system of this invention include:
1. To provide a system based partially on the global positioning system (GPS) or equivalent that permits an onboard electronic system to determine the position of a vehicle with an accuracy of 1 meter or better.
2. To provide a system which permits an onboard electronic system to determine the position of the edges and/or lane boundaries of a roadway with an accuracy of 1 meter or less in the vicinity of the vehicle.
3. To provide a system which permits an onboard vehicle electronic system to determine the position of the edges and/or lane boundaries of a roadway relative to the vehicle with an accuracy of less than 2 meters.
4. To provide a system that substantially reduces the incidence of single vehicle accidents caused by the vehicle inappropriately leaving the roadway at high speed.
5. To provide a system which does not require modification to a roadway which permits high speed controlled travel of vehicles on the roadway thereby increasing the vehicle flow rate on congested roads.
6. To provide a collision avoidance system comprising a sensing system responsive to the presence of at least one other vehicle in the vicinity of the equipped vehicle and means to determine the location of the other vehicle relative to the lane boundaries of the roadway and thereby determine if the other vehicle has strayed from its proper position on the highway thereby increasing the risk of a collision, and taking appropriate action to reduce that risk.
7. To provide a means whereby vehicles near each other can communicate their position and/or their velocity to each other and thereby reduce the risk of a collision.
8. To provide a means for accurate maps of a roadway can be transmitted to a vehicle on the roadway.
9. To provide a means for weather, road condition and/or similar information can be communicated to a vehicle traveling on a roadway plus means within the vehicle for using that information to reduce the risk of an accident.
10. To provide a means and apparatus for a vehicle to precisely know its location at certain positions on a road by passing through or over an infrastructure based local subsystem thereby permitting the vehicle electronic systems to self correct for the satellite errors making the vehicle for a brief period its own DGPS station.
11. To utilize government operated navigation aid systems such as the WAAS and LARS as well as other available or to become available systems to achieve sub-meter vehicle location accuracies.
12. To utilize the OpenGIS(trademark) map database structure so as to promote open systems for accurate maps for the RtZF(trademark) system.
In contrast to some prior art systems, with the RtZF(trademark) system of this invention, especially when all vehicles are appropriately equipped, automatic braking of the vehicle should rarely be necessary and steering and engine control should in most cases be sufficient to prevent accidents. In most cases, braking means the accident wasn""t anticipated.
It is important to understand that this is a process control problem. The process is designed so that it should not fail and thus all accidents should be eliminated. Events that are troublesome to the system include a deer running in front of the vehicle, a box falling off of a truck, a rock rolling onto the roadway and a catastrophic failure of a vehicle. Continuous improvement to the process is thus required before these events are substantially eliminated. Each individual driver is part of the system and upon observing that such an event has occurred he or she should have the option of stopping the process to prevent or mitigate an emergency. All equipped vehicles therefore have the capability of communicating that the process is stopped and therefore that the vehicle speed, for example, should be substantially reduced until the vehicle has passed the troubled spot or until the problem ceases to exist. In other words, each driver is part of the process.
The RtZF(trademark) system of this invention will thus start simple by reducing single vehicle accidents and evolve. The system has the capability to solve the entire problem by eliminating automobile accidents.
This invention is a method and apparatus for eliminating accidents by accurately determining the position of a vehicle, accurately knowing the position of the road and communicating between vehicles and vehicle and the infrastructure. People get into accidents when they go too fast for the conditions and when they get out of their corridor. This invention eliminates these and other causes of accidents. In multilane highways, this system prevents people from shifting lanes if there are other vehicles in the blind spot, thus, solving the blind spot problem. The vehicle would always be traveling down a corridor where the width of the corridor may be a lane or the entire road width or something in between depending on road conditions and the presence of other vehicles.
The invention is implemented through the use of both an inertial navigation system (INS) and a DGPS with carrier frequency enhancement. Due to the fact that the signals from at least four GPS or GLONASS satellites are not always available and to errors caused by multiple path reception from a given satellite, the DGPS systems cannot be totally relied upon. Therefore the INS is a critical part of the system. This will improve as more satellites are launched and additional ground stations are added. It will also significantly improve when the WAAS system in implemented and refined to work with land vehicles as well as airplanes.
Other improvements will now be obvious to those skilled in the art. The above features are meant to be illustrative and not definitive.